In Gaskell's Words: Lady Cumnor

Lady Cumnor having married her two eldest daughters, found her labors as a chaperone to Lady Harriet, the youngest, considerably lightened by co-operation; and, at length, she had leisure to be an invalid. She was, however, too energetic to allow herself this indulgence constantly; only she permitted herself to break down occasionally after a long course of dinners, late hours, and London atmosphere: and then, leaving Lady Harriet with either Lady Cuxhaven or Lady Agnes Manners, she betook herself to the comparative quiet of the Towers, where she found occupation in doing her benevolence, which was sadly neglected in the hurly-burly of London.

Wives and Daughters
Chapter VIII, Drifting Into Danger